报错：Welcome to emergency mode! After logging in, type "journalctl -xb" to view system logs, "systemctl reboot" to reboot, "systemctl default" or ^D to try again to boot into dafault mode. Press Enter for maintenance (or press control-D to continue):
Cause: An error in the disk caused a problem with the file system, and the system failed to start.
Solution: Manually check and repair the disk.
step:
1. Enter to enter the command line. First look at which hard disk has the problem: $ sudo fdisk -l
The problem will be displayed in red. If it is a mobile hard disk, you can unplug it and restart (ctrl + alt + del) to try.
You can also use the command: $ journalctl -xb
Keep pressing Enter to view the log until a red error line appears. See which disk is the problem.
2. If it still doesn't work. Then unmount the hard disk in error $ umount / dev / sdc (corresponding to the device you own error);
3. Check and fix the error: $ fsck -y / dev / sdc
4. Restart: $ sudo shutdown -r now
Thanks: https://www.jianshu.com/p/7433e0bb38e9
